Safety back-off tool for removing pump rods in oil wells



June 5 1956 c. WALL SAFETY BACK-OFF TOOL. FOR REMOVING BUMP RODS IN OILWELLS 3 Sheets-Sheet 1 Filed Aug. 9, 1954 IN VENTOR June 5, 1956 c WALL2,749 091 sAFETs? BACK-OFF TOOL FOR REMOVING PUMP RODS IN OIL WELLSFiled Aug. 9, 1954 3 Sheets-SheetZ ATTORNH June 5, 1956 c. WALL SAFETYBACK-OFF TOOL FOR REMOVING PUMP RODS IN OIL WELLS 5 Sheets-Sheet 3 FiledAug. 9, 1954 WIII/AW INVENTOR ATTORNE respect to the view in Fig. 1;

SAFETY BACK-OFF TOOL FOR REMOVING PUMP RODS IN OIL WELLS Curtis Wall,Winnsboro, Tex.

Application August 9, 1954, Serial N 0. 448,567

4 Claims. (Cl. 255-35) My invention relates broadly to oil wellinstallations and more particularly to a construction of tool forfacilitating the stripping of oil wells.

One of the objects of my invention is to provide a construction ofsafety back-off tool for facilitating the stripping of oil wells whileeliminating the danger of back-lash and tension on the rods, whichgenerally occurs in stripping operations.

Another object of my invention is to provide a construction of safetyback-off tool for stripping oil wells in which the power for operatingthe tool is secured from the conventional draw-works without thenecessity of applying manual effort to the tool.

Still another object of my invention is to provide a construction ofsafety back-off tool for stripping oil wells which includes an actuatingdrum around which a cable is wound preparatory to an unwinding operationunder power secured from the conventional draw-Works with means on thedrum for positively separating the groups of turns of the cable whereone group connects with the cathead on the draw-works for applying arotative force to the drum and the other group of the turns leading tothe tail line, the drum being associated with spaced arms engaging ahand wheel associated with the pump rod and operative to establishclamping connection with the pump rod for transmission thereto of adriving force applied to ing by reference to the accompanying drawings,in which:

Fig. 1 is an elevational view of the safety back-ofl? tool of myinvention as applied to an oil well for stripping the rods therefrom;

Fig. 2 is an elevational view similar to the view shown in Fig. 1 buttaken from a position revolved 90 with Fig. 3 is a horizontal sectionalview taken substantially on line 3+3 of Fig. 2 and showing moreparticularly the manner in which a positive driving force is applied tothe Fig. 4 is a transverse sectional view taken substantially on line 44of Fig. 2 and illustrating particularly the manner in which the pump rodis clamped by a torqueapplying wheel for tensioning the pump rod withrespect to the oil well casing in effecting the unscrewing thereof;

Fig. 5 is a fragmentary perspective view of the safety back-off tool ofmy' invention applied to the pump rod and oil well casing of an oil wellinstallation;

Fig. 6 is an enlarged vertical sectional view of the safety back-offtool of my invention as applied to the upper end of a casing of an oilwell, the view being taken substantially on line 66 of Fig. 7;

United States Patent,

2,749,69l Patented June 5, 1956 Fig. 7 is a fragmentary transversesectional view taken substantially on line 77 of Fig. 6 and showingparticularly the reversible dog provided on the tool of my invention;and

Fig. 8 is a horizontal sectional view on line 8-8 of Fig. 1, showing thearrangement of bracket for supporting the line guide with respect to thecable drum in the tool of my invention.

My invention is directed to the construction of an improved tool for usein stripping oil wells with a high degree of safety. In the operation ofoil wells there are times when the oil pump in the well cannot beunseated and it is necessary to back the rods off in the hole. This isusually accomplished by use of a rod Wheel or pipe wrenches. This typeof operation is very dangerous because the back-lash and tension on therods causes the wheel to jump or whip when the rods are backed-off and agreat number of accidents have resulted to the operating personnel. Suchoperations have required a relatively long period of shutdown of the oilwell and has required the time of four to five men to keep the rod wheelturning until the rods are raised and unscrewed. The safety back-01ftool of my invention eliminates the danger to personnel with respect tothe whipping or jumping of the rod wheel because it is unnecessary thatany one remain in contact with the tool during the back-01f operation,and the motive power for driving the rod wheel is supplied from theconventional draw-works which performs substantially all of the workmechanically instead of the requirement for manual effort heretoforenecessary. Two men can easily accomplish a stripping job with the toolequipment of my invention which heretofore required the services of fourto five men; and the two men can complete the stripping job within lesstime than heretofore required by the services of four to five men.

The tool comprises a drum which is rotatably mounted on the upper end ofan oil well casing and revolvable by a cable system operated from theconventional drawworks of the oil well machinery. The drum carries apair of upright spaced arms which engage the radially extending spokesof the rod wheel which is clamped to a section of the rod for impartingpositive movement to the rod system for successively unscrewing thesections of the rod as the rod is raised from the oil well. Specialprovision is made for eliminating the effects of back-lash byintroducing a ratchet device between the rotatable drum and the oil Wellcasing, whereby the rod wheel operates unidirectionally and does notjump or back-lash and thus become a source of danger or accident tosupervising personnel. The drum is provided with a special form of cableguide for separating the wrapped turns of the cable on that part of thedrum to which the turning efiort is applied from the cathead asdistinguished from that part of the drum where the cable leads to thetail line. The ratchet is reversible so that the unidirectionaloperation may be either clockwise or counter-clockwise. The tool isreadily applied to or removed from the oil well casing when it isnecessary to perform a stripping or assembly operation.

Referring to the drawings in more detail, reference character 1designates the mandrel leading to the oil well casing, the mandrel beingexternally screw-threaded at its upper extremity, as represented at In,and having a vertically extending key slot 1b therein for receiving akey 4a which serves to secure spur gear 4 in non-rotative relationadjacent the top of the mandrel 1. The spur gear 4 rests against thebronze thrust bushing 5 which spaces spur gear 4 from the bronze bearingsleeve 6 around which the drum 7 revolves. Another bearing sleeve 8 ismounted on mandrel 1 and secured in position on the mandrel 1 by meansof bronze thrust collar 9. The bearing sleeves 6 and 8 serve as mountingmeans for the revolvable drum 7. The revolvable drum 7 includes a topflange 16 and an outwardly projecting peripheral bottom edge portion 25.The exterior surface 711 of drum 7 serves to receive and support turnsof cable 26 leading to the cathead of the conventional draw-works andextending to the tail line at 26' as represented in Figs. 2.5. Theexterior surface 7a of drum 7 is mounted by means of annular spacingflange 7b on the inner portion of drum 7, whereby drum 7 may revolveabout bronze bushing sleeves 6 and 8.

The lubricating fitting is provided at 11 secured in drum 7 andaccessible through aperture 70 in the exterior surface 7a of drum 7 fordistributing lubricant to the bearing sleeves 6 and 8, insuring rotativemovement of drum 7 against minimum friction. The mandrel also supportsthe guide holder 10 which extends radially from the mandrel 1 to aposition beyond the external surface of drum 7a and provides a mountingmeans for the guide adjusting shaft 17 through the aid of bushing 10awhich is welded or otherwise secured to the holder 10 and which providesa mounting means for the set screw 21 which enables shaft 17 to beadjusted upwardly or downwardly and longitudinally of drum 7 and set ina selected position.

The shaft 17 carries the line guide 22 which is supported thereon bymeans of bolt 20 which passes through a slot 22a in line guide 22,permitting line guide 22 to be adjusted toward and away from theexternal surface 7a of drum 7 and serve as a means for separating theturns of cable 26 extending to the cathead of the draw-works from theturns of cable 26' leading to the tail line. The line guide 22 may beadjusted longitudinally of the surface 7a of the drum by loosening setscrew 21 and changing the position of shaft 17 for sliding the guideline 22 to the desired position on external surface 7a of drum 7. Theline guide 22 prevents the line from climbing the drum. The guide holder10 carries eye-hook 23 which supports hook 24 to which a bacl;up chainmay be attached to prevent the tool from unscrewing to the left.

The top plate 16 of the drum 7 serves as a support for the two uprightarm attaching plates 18 which are segmentally shaped and attached to thetop 16 of drum 7 by suitable screws 18a. Plates 18 support angularlydisposed upright arms 19 which extend between the spokes 27 of the rodwheel 28 for exerting a rotative force on rod wheel 28 from the powerdelivered from the draw-works through cable 26 wrapped on the exteriorsurface 712 of drum 7. The rod wheel 28 is slotted at the peripherythereof as represented at 28a to enable the rod wheel to be slippedtransversely over the sucker rod 29 which passes downwardly through themandrel 1. The sucker rod 29 is suspended through universal joint 30from hook 31 attached to hoist cable 32 leading to the winding drum ofthe draw-works.

The rod wheel 28 is provided with a central vise-like grip for the rod29 consisting of jaws 33 and 34 where jaw 34 is pivoted at 34a in jaw 33and extends radially through operating arm 35 in substantial alignmentwith any one of the spokes 27 of rod wheel 28 and adapted to be securedwith respect to any selected spoke by a revolvable slotted band 36. Band36 may be revolved about operating arm 35 to permit ingress or egress ofany one of the spokes 27 as the jaws 33 and 34 are closed into grippingrelation with the sides of the sucker rod 29.

The direction in which the rotative force from drum 7 is applied to therod wheel 28 is controlled by the reversible ratchet shown more clearlyin Figs. 6 and 7, The ratchet mechanism is contained within a housing 12in which ratchet dog 13 is located, carried by angularly reversibleshaft and ratchet knob 15, normally ejected by the pressure of coilspring 14. The head of ratchet dog 13 shown at 13a coacts with the teethof spur gear 4. The head 13a is so shaped and located that drum 7 mayrevolve in one direction but is locked against rotation in the oppositedirection. By selecting the position of ratchet dog 13 the direction ofdrum 7 is controlled.

The manner of associating the tool of my invention with an oil well isshown more particularly in Figs. 1 and 2 where the casing is representedat 37, terminating in the casing head 38, from which the tubing 39extends and connects with the pumping T 40 from which flow line 41extends with hand valve 42 interposed in the line from which the pipe 43extends. The mandrel 1 fits into the pumping T 40 and terminates in acollar 44 against which the guide holder 10 fits and with respect towhich the sleeve bearings 6 and 8 are mounted, enabling the drum 7 torevolve with respect to the mandrel. The tool is readily mounted withrespect to and removed from the oil well installation.

The operation of the tool of my invention may be carried out in a numberof ways. My tool is particularly effective for disconnecting the suckerrods at a subsurface point. Such sucker rods usually extend from 2500 to8000 feet below the surface and the unscrewing of the rods at such depthis often a difficult and tedious operation. With the tool of myinvention clamped to the upwardly extending sucker rod a rotative forcecan be applied to the sucker rod which is communicated to thesub-surface point where the disconnect can be effected. Whenthedisconnect is effected the sections of the sucker rod are raised fromthe casing section-by-section, and as the joint for each section israised above the end of the mandrel 1, a wrench or clamp is applied tothe section of the sucker rod immediately below the upper end of themandrel for firmly anchoring the lower section of the sucker rod whilethe rotative force is positively applied to the upper section of thesucker rod through the rod wheel 28. As each section is raised, thelower section is clamped while the upper section is revolved undercontrol of the cable 26-26 wrapped around rotatable drum 7. Generallythe weight of the sucker rod below the joint to be unscrewed issufficient to make it unnecessary to clamp the depending sections of thesucker rod against rotation and it is sutlicient to apply the rotativeunscrewing torque to the section of the sucker rod immediately above thejoint to be unscrewed.

In the reverse process the lower section of the sucker rod is clampedfirmly in mandrel 1 while the adjacent upper section is lowered intoposition to be screwed into coupling relationship with the lower sectionof the rod.

While I have described my invention in one of its preferred embodiments,I realize that modifications may be made and I desire that it beunderstood that no limitations upon my invention are intended other thanmay be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. A tool for unscrewing sections of a sectionalized sucker rodcomprising a well structure, a rotary drum adapted to be supported invertical position over the well structure concentrically around thevertically extending scctionalized sucker rod projecting from the wellstructure, a pair of arms projecting vertically from the upper end ofsaid drum, a rod wheel having radially extending spokes, said rod wheelbeing clamped to a section of the sucker rod extending vertically abovethe well structure, said spokes being engageable by said arms whereby arotary torque applied to said drum is imparted to said means and saidspokes to the ole ripcd section of the sucker rod for imparting aturning torque thereto for unscrewing the successive sections of thesucker rod, and a guide holder mounted beneath said drum, said guideholder having a guide adjusting shaft. therein disposed in a positionexternal to said drum and a line guide supported on said guide adjustingshaft and embracing the external surface of said drum whereby a cablewrapped over the external surface of said drum has the turns thereofseparated into sections, one section of which extends to aforce-applying means and the other section of which extends to a tailline.

2. A tool for unscrewing sections of a sectionalized sucker rodcomprising a well structure, a rotary drum areaooi adapted to besupported in vertical position over the well structure concentricallyaround the vertically extending sectionalized sucker rod projecting fromthe well structure, a pair of arms projecting vertically from the upperend of said drum, a rod wheel having radially extending spokes, said rodwheel being clamped to a section of the sucker rod extending verticallyabove the well structure, said spokes being engageable by said armswhereby a rotary torque applied to said drum is imparted to said meansand said spokes to the clamped section of the sucker rod for imparting aturning torque thereto for unscrewing the successive sections of thesucker rod, said drum including a horizontally extending top structureand an outwardly projecting bottom flange for confining the turns of anactuating cable thereon, and a line guide embracing a portion of theexternal surface of the drum for separating said surface into upper andlower portions, the said upper portion receiving the turns of atorqueapplying cable and the lower section of which receives the turnsof the cable leading to a tail line.

3. A tool for unscrewing sections of a sectionalized sucker rodcomprising a Well structure, a rotary drum adapted to be supported invertical position over the well structure concentrically around thevertically extending sectionalized sucker rod projecting from the wellstructure, a pair of arms projecting vertically from the upper end ofsaid drum, a rod wheel having radially extending spokes, said rod wheelbeing clamped to a section of the sucker rod extending vertically abovethe well structure, said spokes being engageable by said arms whereby arotary torque applied to said drum is imparted to said means and saidspokes to the clamped section of the sucker rod for imparting a turningtorque thereto for unscrewing the successive sections of the sucker rod,and a line guide vertically adjustable longitudinally of said drum forseparating the external surface of said drum into an upper and lowerportion, said upper portion being adapted to receive the turns of acable leading to a torqueapplying force and said lower portion beingadapted to receive turns of a cable leading to the tail line.

4. A tool for unscrewing sections of a sectionalized sucker rodcomprising a well structure, a rotary drum adapted to be supported invertical position over the well structure concentrically around thevertically extending sectionalized sucker rod projecting from the wellstructure, a pair of arms projecting vertically from the upper end ofsaid drum, a rod wheel having radially extending spokes, said rod wheelbeing clamped to a section of the sucker rod extending vertically abovethe well structure, said spokes being engageable by said arms wherebyajrotary torque applied to said drum is imparted to said means and saidspokes to the clamped section of the sucker rod for imparting a turningtorque thereto for unscrewing the successive sections of the sucker rod,and wherein said rotary drum has the external surface thereof embracedby a substantially semi-circular member constituting a line guide, andmeans for adjusting said member longitudinally of the drum forseparating said drum into an upper and lower section, said upper sectionreceiving the turns of a force-applying cable and said lower sectionreceiving turns of a cable leading to a tail line.

References Cited in the file of this patent UNITED STATES PATENTS466,653 Chamberlin Ian. 5, 1892 741,925 Oiler Oct. 20, 1903 1,300,995Moody Apr. 15, 1919 1,787,185 Baird Dec. 30, 1930 2,217,238 Sisson Oct.8, 1940

